Examples of such systems include the tire pressure monitoring systems comprising electronic modules mounted on each of the wheels of the vehicles, dedicated to measuring parameters, such as the pressure and/or temperature of the tires fitted on these wheels, and intended to inform the driver of any abnormal variation of the measured parameter.
One of the current solutions most commonly used to ensure the fastening of the electronic modules on the wheel rims consists in producing electronic units each consisting of an electronic module assembled with an inflation valve enabling said electronic module to be attached to the rim of the wheel.
A solution regarding such electronic units consists in producing specific inflation valves capable of ensuring the transmission of the forces to which the electronic modules are subject. However, this solution is costly because, in addition to the high price of the inflation valves, which are usually entirely metallic, it entails producing auxiliary parts (nuts, seals, etc.) specially designed to guarantee a leak-tight fastening of the inflation valves on the rims.
The document US 2004/0206169 (Beru) describes such an inflation valve having a metallic body fastened by a clamping nut at the orifice of the rim. In this document, the inflation valve does not include any elastic part intended to stretch when fitting the valve in the rim. It is not a “snap-in” valve. This means that this type of valve does not have any rod over which the module has to slide when introducing the valve into the rim orifice. The fastening of the module on the valve head does not need to provide an expansion space for the valve during its fitting. Because of this, the means for attaching the module onto the head of this conventional valve can be produced by a simple elastic clasp.
In order to overcome this drawback, a second solution has consisted in producing inflation valves of the same basic design as the conventional inflation valves of “snap-in” type, modified so as to ensure that the forces to which the electronic modules are subject are taken up.
This solution has notably culminated in the production of an electronic unit as described in the patent application WO 2009/007035 comprising:                an electronic module,        an inflation valve of “snap-in” type, comprising:                    a valve body made of an elastomer material, provided with a longitudinal axial bore and intended to extend through an orifice formed in the rim, said valve body consisting of an elastically deformable trunk and an abutment head against the rim, separated from the trunk by a neck designed to be positioned in a leak-tight manner in the orifice formed in said rim,            and a hollow tubular core made of a rigid material, housing a shutting mechanism and with dimensions designed to fit into the bore of the valve body and extend on either side in the extension of said valve body, said tubular core consisting of two longitudinal sections arranged relative to one another and in relation to the valve body, so as to allow an elastic deformation of the trunk capable of enabling the inflation valve to be fitted through the orifice of the rim,                        and means for attaching the electronic module and the inflation valve comprising:                    a ring attached to the electronic module designed to be slideably mounted around the portion of the tubular core extending in the extension of the abutment head of the valve body, in a position of the electronic module in which the latter extends in the direct extension of the inflation valve,                        and assembling means for fitting a hollow sleeve attached to the ring of the electronic module inside an annular chamber formed in the abutment head of the valve body.        
Because of these specific features, and in practice, such an electronic unit has the advantage of guaranteeing a behavior of the inflation valve similar to that of an inflation valve of traditional “snap-in” type.
However, according to this principle, the assembly of the electronic module and of the valve body is done through a link of the fitting type whose resistance is directly linked to the stretch resistance of the elastomer material of the inflation valve. Now, this link has to be dismantleable in order in particular to allow the electronic module to be recovered in the event of damage to the inflation valve. Because of this, it is very difficult to find a resistance trade-off, on the one hand, allowing the two elements to be dismantled, and on the other hand, guaranteeing the strength of the link for high vehicle speeds. For this reason, and in practice, the electronic units comprise an additional removable locking member of the type, as described in the patent application WO 2009/007035, comprising an elastic ring, spring ring of the “lyre” type, “O-clamp” clamping collar, screw clamp, or various types of keyways. However, these additional members require specific tools for their fitting and their removal, and also increase the complexity of the steps for fitting and dismantling the electronic units.